Financial Instruments - Short-term Borrowings (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Financial Instruments [Abstract]
Commercial paper		$ 6,705	$ 3,100
Current portion of long-term debt, principal amount		2,139	4,781
Other short-term borrowings, principal amount	[1]	1,691	966
Total short-term borrowings, principal amount		10,535	8,847
Net fair value adjustments related to hedging and purchase accounting		0	(5)
Net unamortized discounts, premiums and debt issuance costs		(29)	(11)
Total Short-term borrowings, including current portion of long-term debt, carried at historical proceeds, as adjusted	[2]	$ 10,507	$ 8,831

[1] Other short-term borrowings primarily include cash collateral. For additional information, see Note 7E.

[2] Amounts may not add due to rounding.